This is a prospective study designed to examine the associations of antecedents of poor developmental outcome which are defined as cerebral palsy, visual and hearing impairments and cognitive impairment at 18 to 24 months of age (corrected age if applicable) on all infants who were born between September 1993 to March 1994 at Stanford. The role of initial neonatal illness by SNAP (Score for Neonatal Acute Physiology) and CRIB (Clinical Risk Index for Babies) on unfavorable neurodevelopmental outcome will also be examined. With this study, we will be able to identify characteristics of maternal (antepartum and intrapartum), perinatal, and neonatal risk factors among different ethnic groups as well as various birth weight groups to further implement different preventive strategies to target those groups at highest risk.